Photographic developers with titanous diethylenetriaminepentaacetic acid

ABSTRACT

CERTAIN TITANIUM COMPLEX, SILVER HALIDE DEVELOPING AGENTS IN PHOTOGRAPHIC DIFFUSION TRANSFER SYSTEMS PROVIDE STABLE, DEVELOPED IMAGES OVER A BROAD PH RANGE. THEY CAN BE EMPLOYED IN MONOBATHS AND IN COMBINATION WITH VARIOUS ADDENDA, INCLUDING OTHER DEVELOPING AGENTS AND SILVER HALIDE SOLVENTS.

United States Patent "ice 3,723,126 PHOTOGRAPHIC DEVELOPERS WITH TITANOUS DIETHYLENE'IRIAMINEPENTAACE'IIC ACID Harry J. Price, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Oct. 1, 1971, Ser. No. 185,843 Int. Cl. G03c 5/38 U.S. Cl. 9661 M 8 Claims ABSTMCT OF THE DISCLOSURE Certain titanium complex, silver halide developing agents in photographic diffusion transfer systems provide stable, developed images over a broad pH range. They can be employed in monobaths and in combination with various addenda, including other developing agents and silver halide solvents.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to certain titanium complex silver halide developing agents and to photographic diffusion transfer systems containing such developing agents. In one of its aspects the invention relates to a photographic product for a diffusion transfer system containing the described titanium complex, silver halide developing agents. Another of its aspects relates to a monobath containing the titanium complex, silver halide developing agents with a silver halide solvent. A further aspect relates to a diffusion transfer process, preferably a silver salt diffusion transfer process employing the titanium complex, silver halide developing agents.

Description of the state of the art In recent years diffusion transfer photographic systems, processes, compositions and elements for such systems have become well known. A diffusion transfer system, in brief, is characterized by the use of a photographic emulsion layer and an image receiver or precipitating layer contiguous to the emulsion layer. After exposure of the photographic emulsion layer, typically a processing composition, such as a developer composition, is applied between the exposed photographic emulsion layer and the image receiver or precipitating layer. The processing composition usually contains a silver halide solvent, such as sodium thiosulfate, which causes the unexposed silver salts to dissolve forming a silver complex which diffuses to the image receiver or precipitating layer where development nuclei or an image precipitating agent in that layer causes the silver to be precipitated or deposited from the silver complex imagewise. Development nuclei or precipitating agents can be present in the image receiving layer before contact with the complexed silver or the nuclei can be formed in situ.

Difiusion transfer photographic processes, elements and compositions for such processes are well known and described, for example, in U.S. Pat. 2,698,237 of Land issued Dec. 28, 1954; US. Pat. 2,647,056 of Land issued July 28, 1953; and US. Pat. 3,345,166 of Land issued Oct. 3, 1967. More recent diffusion transfer systems are described, for example, in Belgian Pat. 746,700, published Apr. 30, 1970; Belgian Pat. 749,933, published July 15, 1970; Belgian Pat. 749,934, published July 15, 1970' and Belgian Pat. 749,935, published July 15, 1970.

The requirements for developing agents for diffusion transfer systems are very stringent and relatively few of the developing agents which are satisfactory for general silver halide developing processes are satisfactory for diffusion transfer systems without providing undesired results, such as undesired relative speed, maximum density, gamma, stain, or undesired stability. One of the diffusion 3,723,126 Patented Mar. 27, 1973 transfer developing agents used more successfully is a 2,4-diaminophenol such as 2,4-diaminophenol dihydrochloride. However, although such developing agents will produce a positive image, they are subject to rapid oxidation which results in an unsightly and objectionable dark oxidation product which stains the positive print.

Certain titanium and other metal complexes, such as metal chelates have been employed as silver halide developing agents in conventional silver halide development solutions before. This is described in French Pat. 1,064,- 698 published May 17, 1954; British Pat. 720,235 published Dec. 15, 1954; and US. Pat. 3,295,978 of Barr issued Jan. 3, 1967. None of these relate to diffusion transfer systems.

A titanous complex with ethylenediaminetetraacetic acid has been employed in a silver salt diffusion transfer system, as described in U.S. Pat. 3,017,270 of Tregillus et a1. issued Jan. 16, 1962. However, this titanous complex does not provide desired improved image tone, higher contrast, higher photographic speed, with improved minimum density. This is demonstrated in following Example 2.

There has been a continuing need for titanous ion complex silver halide developing agents which provide desired photographic speed, contrast, improved image tone, without increased minimum density in a silver salt diffusion transfer system. There has also been a need for such a developing agent which can provide a developed image in a silver salt diffusion transfer system in combination with other developing agents and which eliminates the need for alkaline development activators in the described processing compositions and systems.

SUMMARY OF THE INVENTION According to the invention, desired photographic speed, contrast and improved image tone, without increased minimum density, with a broad pH range for processing is provided in a silver salt diffusion transfer system, including photographic products, elements, processing compositions and processes, by employing a titanous complex silver halide developing agent which is a titanous diethylenetriaminepentaacetic acid complex. The described titanous complex silver halide developing agent surprisingly can develop a latent image employing a broad pH range, e.g., a pH of about 1 to about 10.

These developing agents can be employed in combination with other components in a silver salt diffusion transfer system, such as other silver halide developing agents.

DETAILED DESCRIPTION OF THE INVENTION The described titanous complex, silver halide developing agents, also known as titanium (III) complex silver halide developing agents employed according to the invention are typically prepared by reacting a titanous salt, also known as a titanium (III) salt, with a suitable ligand to provide a complex which has desired silver halide developing activity in a silver salt diffusion transfer systern. The titanous salt can be, for example, titanous chloride, also known as titanium (III) chloride, titanous sulfate or titanous bromide. The preparation of titanous diethylenetriaminepentaacetic acid (DTPLA) complex employing titanous chloride is exemplary of the preparation of the titanous complex, silver halide developing agent useful in the practice of the invention. According to this preparation, diethylenetriaminepentaacetic acid is suspended in water. An amine, such as allylamine, is added to dissolve the DTPA and increase the pH of the DTPA solution. The resulting solution can be flushed with nitrogen gas. An aqueous solution of titanous chloride is then added to the resulting solution in a concentration ratio which provides up to equal molar ratios of titanous ion to ligand atom. Additional amine can be added to a'zza, 126

adjust the pH of the resulting solution to about 7. If desired, other acid compounds can be added to the solution to provide a lower pH, such as a pH to about Titaneous complexes are also described in the British Journal of Photography, Vol. 103, No. 5021, pages 384 386 and 392, Aug. 10, 1956.

Suitable diffusion transfer systems, processes, processing compositions and elements, therefore, which can be employed in the practice of the invention are described, for example, in U.S. Pat. 2,452,181 of Land issued Feb. 27, 1951; U.S. Pat. 3,337,342 of Green issued Aug. 27, 1967; Belgian Pat. 746,700 published Apr. 30, 1970; Belgian Pat. 749,934 published July 15, 1970; Belgian Pat. 749,933 published July 15, 1970; Belgian Pat. 749,935 published July 15, 1970 and Belgian Pat. 739,706 published Dec. 15, 1969. The described developing agents can be used in so-called high speed diffusion transfer processes and compositions, therefore, as described, for example, in U.S. Pat. 3,326,683 of Land et al. issued June 20, 1967; or in other types of diffusion transfer systems, processes and compositions, therefore, such as described in U.S. Pat. 2,857,274 of Land et al. issued Oct. 21, 1958; U.S. Pat. 3,020,155 of Yackel et al. issued Feb. 6, 1962; and U.S. Pat. 2,584,030 of Land issued Jan. 29, 1952. These references also describe the typical photographic products suitable for diffusion transfer systems comprising in combination (a) photographic element comprising a photographic silver salt layer, e.g., a photographic silver halide layer, (13) a processing composition containing a silver halide solvent, typically in a rupturable container and (c) an image receiving layer. The described titanous complex, silver halide developing agents are suitable in the developing processing composition.

Other developing agents can be employed in the practice of the invention in a range of physical locations in a diffusion transfer photographic system to provide a combination of developing agents with the described titanous complex, silver halide developing agents. One or more of the other developing agents can be employed in one or more layers of the photographic element and/ or in a processing composition and/or in an image receiving layer, if desired. The optimum location will depend upon the desired image, processing conditions, the particular developing agent combination employed and the like. For example, the titanous complex, silver halide developing agent can be employed in the described processing composition and another developing agent or agents can be employed in the processing composition and/or incorporated in one or more layers of the photographic element.

Accordingly, one embodiment of the invention is: in a photographic product comprising, in combination, (a) a photographic element comprising photographic silver halide, (b) a processing composition containing a silver halide solvent, and (c) an image receiver layer, the photographic product comprising a titanous complex silver halide developing agent, the improvement wherein the described silver halide developing agent is a titanous diethylene triaminepentaacetic acid complex.

The developing agents employed in the practice of the invention can be employed for developing an image in a range of photographic emulsions in a diffusion transfer system, as described.

The silver halide emulsions employed with this invention can comprise silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions can be coarse or fine grain and can be prepared by any of the well-known procedures employed in emulsion making such as single-jet emulsions, doublejet emulsions such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thioether ripened emulsions, such as those described in U.S. Pat. 2,222,264 of Nietz et al. issued Nov. 19, 1940; U.S. Pat. 3,320,069 of Illings- Worth issued May 16, 1967; and U.S. Pat. 3,271,157 of McBride issued Sept. 6, 1966. Surface image emulsions can be used or internal image emulsions such as those described in U.S. Pat. 2,592,250 of Davey et al. issued Apr. 8, 1952; U.S. Pat. 3,206,313 of Porter et al. issued Sept. 14, 1965; U.S. Pat. 3,367,778 of Berriman et al. issued Feb. 6, 1968; and U.S. Pat. 3,447,927 of Bacon et al. issued June 3, 1969. Negative type emulsions can be used or direct positive emulsions, such as those described in U.S. Pat. 2,184,013 of Leermakers issued Dec. 19, 1939; U.S. Pat. 2,541,472 of Kendall et al. issued Feb. 13, 1951; British Pat. 723,019 of Schouweneaars; French Pat. 1,520,785 published Mar. 4, 1968; and U.S. Pat. 2,861,885 of Land issued Dec. 8, 1953.

The emulsions used with this invention can be sensitized with chemical sensitizers such as with reducing agents; sulfur, selenium or tellurium compounds; gold, platinum or palladium compounds; or combinations of these. Suitable procedures for chemical sensitization are described in U.S. Pat. 1,623,499 of Sheppard issued Apr. 5, 1967; U.S. Pat. 2,399,083 of Waller et al. issued Apr. 23, 1946; U.S. Pat. 3,297,447 of McVeigh issued Jan. 10, 1967; and U.S. Pat. 3,297,446 of Dunn issued Jan. 10, 1967.

The silver halide emulsions, processing compositions and/or image receivers used in the practice of the invention can contain speed increasing compounds such as polyalkylene glycols, cationic surface active agents and thioethers or combinations of these as described in U.S. Pat. 2,886,427 of Piper issued May 12, 1959; U.S. Pat. 3,046,134 of Dann et al. issued July 24, 1962; U.S. Pat. 2,944,900 of Carroll et al. issued July 12, 1960; and U.S. Pat. 3,294,540 of Goffe issued Dec. 27, 1966.

The silver halide emulsions and image receivers used in the practice of the invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers each used alone or in combination include thiazolum salts described in U.S. Pat. 2,131,038 of Brooker et al. issued Sept. 27, 1938 and U.S. Pat. 2,694,716 of Allen issued Nov. 16, 1964; the azaindenes described in U.S. Pat. 2,86,437 of Piper issued May 12, 1959 and U.S. Pat. 2,444,605 of Heimbach issued July 6, 1948; the mercury salts as described in U.S. Pat. 2,728,663 of Allen et al. issued Dec. 27, 1955; the urazoles described in U.S. Pat. 3,287,135 of Anderson issued Nov. 22, 1966; the sulfocatechols described in U.S. Pat. 3,236,652 of Kennard et al. issued Feb. 22, 1966; the oximes described in British Pat. 623,448 published May 1-9, 1949; nitron; nitroindozoles; the mercaptotetrazoles described in U.S. Pat. 2,403,927 of Kendall et al. issued July 16, 1946; U.S. Pat. 3,266,897 of Kennard et al. issued Aug. 16, 1966 and U.S. Pat. 3,397,987 of Luckey et al. issued Aug. 20, 1968; the polyvalent metal salts described in U.S. Pat. 2,893,405 of Jones issued June 17, 1958; the thiuronium salts described in U.S. Pat. 3,220,839 of I-Ierz issued Nov. 30, 1965; the palladium, platinum and gold salts described in U.S. Pat. 2,566,263 of Trivelli et al. issued Aug. 28, 1951 and U.S. Pat. 2,597,915 of Yutzy et al. issued May 27, 1952.

The photographic and other hardenable layers employed in a photographic element or image receiver in the process of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as the aldehydes and blocked aldehyde, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinyl sulfones, active halogen compounds, epoxy compounds, azaindenes, active olefins, isocyanates, carbodiimides, mixed-function hardeners and polymeric hardeners such as oxidized polysaccharides like dialedhyde starch, oxyguragum and the like.

The photographic emulsions and elements including image receivers described, employed in the practice of this invention, can contain various colloids alone or in combination as vehicles, binding agents and various layers. Suitable hydrophilic materials include both naturally occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as water-soluble polyvinyl compounds like poly(vinylpyrrolidone), acrylamide polymers and the like.

The described photographic emulsion layers, image receivers and other layers of a photographic element employed in the practice of this invention can also contain, alone or in combination with hydrophilic, water-permeable colloids, other synthetic polymeric compounds such as dispersed vinyl compounds, such as in latex form and particularly those which increase the dimensional stability of the photographic materials. Suitable synthetic polymers include those described, for example, in U.S. Pat. 3,142,- 568 of Nottorf issued July 28, 1964; U.S. Pat. 3,193,386 of White issued July 6, 1965; U.S. Pat. 3,062,674 of Houck et al. issued Nov. 6, 1962; U.S. Pat. 3,220,844 of Houck et al. issued Nov. 30, 1965; U.S. Pat. 3,287,289 of Ream et al. issued Nov. 22, 1966; and U.S. Pat. 3,411,911 of Dykstra issued Nov. 19, 1968. Particularly effective are those water insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkylacrylates or methacrylates, those which have cross-linking sites which cilitate hardening or curing and those having recurring sulfobetaine units as described in Canadian Pat. 774,- 054.

The photographic elements and images receivers used in the practice of the invention can contain antistatic or conducting layers. Such layers can comprise soluble salts such as chlorides, nitrates and the like, evaporated metal layers, ionic polymers such as those described in U.S. Pat. 2,861,- 056 of Minsk issued Nov. 18, 1958 and U.S. Pat. 3,206,- 312 of Sterman et al. issued Oct. 14, 1965 or insoluble inorganic salts such as those described in U.S. Pat. 3,428,- 451 of Trevoy issued 'Feb. 18, 1969.

The photographic elements, and/ or image receivers and other layers of a photographic elemnt employed and described herein can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinylacetal) film, polystyrene film, poly(ethyleneterephthalate) film, polycarbonate film, and related films or resinous materials, as well as glass, paper, metal and the like. Typically a flexible support is employed, especially a paper support, which can be partially acetylated or coated with baryta and/ or an alpha olefin polymer, particularly a polymer of an alpha olefin containing 2 to carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymers and the like.

The photographic layers and/or image receiver layers employed in the practice of this invention can contain plasticiers and lubricants such as polyalcohols, e.g., glycerin and diols of the type described in U.S. Pat. 2,960,- 404 of Milton issued Nov. 15, 1968; fatty acids or esters such as those described in U.S. Pat. 2,588,765 of Robijns issued Mar. 11, 1952 and U.S. Pat. 3,121,060 of Duane issued Feb. 11, 1964 and silicone resins such as those described in British =P'at. 955,061.

The photographic layers, processing compositions and/ or image receivers employed in the practice of this invention can contain surfactants such as saponin, anionic compounds such as alkyl or aryl sulfonates described in U.S. Pat. 2,600,831 of Baldsiefen issued June 17, 1952 and amphoteric compounds such as those described in U.S. Pat. 3,133,816 of Ben-Ezra issued May 19, 1964.

The photographic elements and/or image receivers used in the practice of the invention can contain' brightening agents including stilbene, triazene, oxazole, and coumarin brightening agents. Water-soluble brightening agents can be used such as those described in German Pat. 972,067 and U.S. Pat. 2,933,390 of McFall et al.

issued Apr. 19, 1960 or dispersions of brighteners can be used, such as those described in German Pat. 1,150,- 274 and U.S. Pat. 3,406,070 of Oetiker et al. issued Oct. 15, 1968 and French Pat. 1,530,244.

The light-sensitive silver halide emulsions employed in the practice of the invention can be X-ray or other nonspectrally sensitized emulsions. They also can contain spectral sensitizing dyes and be conveniently orthosensiized or pansensitized with such dyes. For instance, these emulsions can be spectrally sensitized by treating with a solution of a sensitizing dye in an organic solvent or the dye can be added in the form of a dispersion as described in British Pat. 1,154,781 of Owens et al. For optimum results, the dye can either be added to the emulsion as a final step or at some earlier stage. Sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pat. 2,526,632 of Brooker et al. issued Oct. 24, 1950; U.S. 2,503,776 of Sprague issued Apr. 11, 1950; U.S. 2,493,748 of Brooker et al. issued Jan. 10, 1950 and U.S. 3,384,486 of Taber et a1. issued May 21, 1968. Spectral sensitizers which can be used include the cyanines, mercocyanines, complex (trinuclear or tetranuclear) merocyanines, complex (trinucelar or tetranuclear) cyanines, homopolar cyanines, styryls, and hemicyanines, e.g., enamine hemicyanines, oxonols and hemioxonols. The cyanines can contain such basic nuclei as thiozolines, pyrrolines, pyridines, oxazoles, thiazoles, selenazoles and oxazolines, selenizoles, and imidizoles. Such n-uclei can contain sulfoalkyl; carboxyalkyl and alkylamino groups and can be fused to benzene or naphthalene rings either unsubstituted or substituted with halogen, phenyl, alkyl or alkoxy groups. The dyes can be symmetrical or unsymmetrical and can contain alkyl, phenyl or heterocyclic substituents on the polymethine chain. The merocyanine dyes can contain the basic nuclei mentioned as well as acid nuclei such as thiohydantoins, rhodanines, oxazolidenediones, barbituric acids, thiazolineones and malononitrile.

These acid nuclei can be substituted with alkyl, alkylene, phenyl, carboxyalkyl, sulfoalkyl, hydroxyalkyl, alkoxyalkyl, alkylamino groups or heterocyclic nuclei.

Combinations of these dyes can be used, if desired. In addition, supersensitizing addenda which do not absorb visible light can be included, for instance, ascorbic acid derivatives, azaindenes, cadmium salts, and organic sulfonic acids as described in U.S. Pat. 2,933,390 of McFall et al. and U.S. Pat. 2,937,089 of Jones et al. issued May 17, 1960.

The various addenda including sensitizing dyes employed in the practice of this invention can be added to the photographic emulsion and/or other layers of a photographic element and/ or image receiver from water solutions or suitable organic solvent solutions. The corn pounds can be added using various procedures including those described in U.S. Pat. 2,912,343 of Collins et al. issued Nov. 10, 1959; U.S. Pat. 3,342,605 of McCrossen et al. issued Sept. 19, 1967; U.S. Pat. 2,996,287 of Audran issued Aug. 15, 1961 and U.S. Pat. 3,425,835 of Johnson et al. issued Feb. 4, 1969.

The layers of a photographic element and/or image receiver used in the practice of the invention can be coated by various coating procedures including dip coating, airknife coating, curtain coating, or extrusion coating using hoppers of the type described in U.S. Pat. 2,681,294 of Beguin issued June 15, 1954. If desired, two or more layers can be coated simultaneously by the procedures described in U.S. Pat. 2,761,791 of Russell issued Sept. 4, 1956 and British Pat. 837,095.

The described developing agents employed in the practice of the invention can be used in colloid transfer processes. They can also be used in photographic elements and/or in processing compositions intended for use in monobath processing such as described in U.S. Pat. 2,875,048 of Haist et al. issued Feb. 24, 1959 and British Pat. 1,063,844 of Beavers et al. published Mar. 30, 1967.

The described developing agents employed in the practice of the invention can also be used in multilayer, single element diffusion transfer systems which utilize undeveloped silver halide in non-image areas of a negative to form a positive by physical development of this silver onto a nuclei containing, contiguous, image receiving layer after which the upper layer is removed by scrubbing, Washing, stripping or other suitable method. Processes of this type are described, for instance, in US. Pat. 3,020,155 of Yackel et al. issued Feb. 6, 1962. Useful results are obtained in elements of this type when they are processed, for example, by use of a so-called external processing web containing the described developing agents in combination with a silver halide solvent and other processing or coating components dispersed in a vehicle and coated on a suitable support. Processing webs of this type are described, for example, in US. Pat. 3,179,517 of Tregillus et al. issued Apr. 20, 1965.

The developing agents employed in the practice of the invention can be employed, if desired, in photographic elements designed for stabilization type processing. For example, they can be incorporated in one or more layers of a photographic element which is exposed, and then processed by contact with a mildly alkaline development activator, and followed by stabilization with a suitable stabilizer such as a thiocyanate or thiosulfate stabilizer, e.g., by contact with a thiocyanate or thiosulfate solution containing ammonium thiocyanate or sodium thiosulfate. Such processes are described, for example, in US. Pat. 3,326,684 of Nishio et al. issued June 29, 1967; British Pat. 1,004,302 of Ilford published Sept. 15, 1965; French Pat. 1,516,556 of Fassbender; and in an article by H. D. Russell et al. in P.S.A. Journal, Volume 8, No. 50, pages 59-62, entitled Stabilization Processing of Films and Papers.

Development nuclei or silver precipitating agents which can be employed in diffusion transfer systems, as described, can be physical development nuclei or chemical precipitants including, for example: (a) heavy metals in colloidal form and salts of these metals, (b) salts of amines which form silver salts and/or ((1) non-diffusing polymeric materials with functional groups capable of combining with silver amines.

Suitable development nuclei and/or silver image precipitating agents within the described classes include metal sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, stannous halides, sulfur, gold, platinum, palladium, and mercury, colloidal sulfur, aminoguanidine sulfate, aminoguanidine carbonate, arsenous oxide, sodium stannite, hydrazines, xanthates, and similar agents disclosed, for example, in US. Pat. 3,020,155 of Yackel et al. issued Feb. 6, 1962. A nondiffusing polymeric silver precipitant or development nuclei, such as poly(vinylmercaptoacetate) can also be employed.

A wide range of concentrations of development nuclei or silver precipitating agents can be employed. A coricentration of the development nuclei or silver precipitate in the image receiving layer must be at least sufiicient to insure the development of a positive image and sutficient removal of undeveloped silver salt from the lightsensitive layer to be processed. Usually, the concentration of development nuclei, as described, is about 5 micrograms to about 5 milligrams per square foot of the layer containing the precipitants or development nuclei.

The developing agents employed in the practice of the invention can be employed in combination with other silver halide developing agents. The developing agents employed in the practice of the invention can be employed in such combinations as auxiliary developing agents or as the main component of the developing agent combination. Suitable silver halide developing agents which can be employed in combination with the described developing agents include, for example, polyhydroxybenzenes such as hydroquinone developing agents, e.g., hydroquinone, tertiary butyl hydroquinone; catechol and pyrogallol; chloro-substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy substituted hydroquinones such as methoxyhydroquinone or ethoxyhydroquinone; aminophenol developing agents such as 2,4-diaminophenols and methylaminophenols; ascorbic acid developing agents such as ascorbic acid, ascorbic acid ketals, and ascorbic acid derivatives such as those described in US. Pat. 3,337,342 of Green issued Aug. 22, 1967; hydroxylamine developing agents such as N,N-di(2ethoxyethyl)hydroxylamine and/or N,N-diethylhydroxylamine; B-pyrazolidone developing agents such as l-phenyl-3-pyrazolidone and l-phenyl-4-methyl- 4-hydroxymethyl-3-pyrazolidone, including those described in British Pat. 930,572 published July 3, 1963. Such developing agents can be used alone or in combination. It is usually desirable to use other developing agents than aminophenol compounds because of the tendency of these compounds to cause undesired stain.

The described developing agents are also useful in combination with a reductone silver halide developing agent, especially an anhydro dihydro amino reductone silver halide developing agent. A range of reductone silver halide developing agents can be employed in the practice of the invention. These include any reductone silver halide developing agents, especially anhydro dihydro amino reductone silver halide developing agents, which provide desired developing activity such as those described in Belgian Pat. 749,935 issued July 15, 1970.

The described reductone silver halide developing agents which can be employed in the practice of the invention are typically amino hexose reductones, especially anhydro dihydro amino hexose reductones. Such compounds are usually derived from sugars, especially D-glucose although other 6-carbon or hexose reducing sugars such as D-galactose, D-mannose, Dfructose, L-sorbose, or the like can be used. A suitable method for preparing the described amino hexose reductones and anhydro amino hexose reductones is set out in US. Pat. 2,936,308 of Hodge issued May 10, 1960. Corresponding anhydro dihydro amino reductones can be prepared from corresponding anhydro amino reductones by a process of hydrogenation in the presence of a suitable catalyst such as Raney nickel. This is described, for example, in Tetrahedon, volume 6, pages 123-138 (1959).

Another embodiment of the invention is a photographic processing composition, suitable for the described diffusion transfer system, comprising a silver halide solvent and a titanous diethylenetriaminepentaacetic acid complex, silver halide developing agent, as described. This composition can be a monobath which is suitable for processing photographic elements other than those employed in diffusion transfer systems.

The described processing composition is typically employed in a combination of (a) a photographic element comprising a photographic silver halide, (b) a viscous processing composition comprising a silver halide solvent, such as sodium thiosulfate, and a titanous diethylenetriaminepentaacetic acid complex, silver halide developing agent, as described, and (c) an image receiving layer comprising development nuclei, especially palladium development nuclei, dispersed in a polymeric binder.

A processing composition employed in the practice of the invention is typically a viscous processing composition. A wide range of viscosity can be employed. The viscosity can be about 20 to about 100,000 centipoises. typically about to about 10,000. Various thickening agents are suitable in the described processing compositions and processes of the invention. Any of those commonly employed in diffusion transfer photographic systems can be employed, as well as those employed in viscous monobaths. These include those described, for example, in US. Pat. 3,120,795 of Land et al. issued Feb. 11, 1964, e.g., hydroxyethyl cellulose and carboxymethyl cellulose.

Suitable viscous monobaths in which the described combination of developing agents can be employed are set out, for example, in the Monobath Manual by Grant M.

9 Haist (1966), and US. Pat. 3,392,019 of Barnes et al. issued July 9, 1968.

A wide range of silver halide solvents can be employed in the practice of the invention, especially those which are active as a pH less than 11.0. Usually, the silver halide solvent is a water soluble thiosulfate, such as sodium thiosulfate, however, various organic silver halide complexing agents, such as those described in Haist et al., Photographic Science and Engineering, volume 5, page 198 (1961), described in French Pat. 1,312,687 issued Nov. 12, 1962 and described in Belgian Pat. 606,559 of Ulrich et al. issued July 26, 1960 and similar agents can also be used.

Another emobdiment of the invention is a photographic element comprising a support, photographic silver halide and a titanous diethylenetriaminepentaacetic acid complex, silver halide developing agent, as described.

A further embodiment of the invention is a photographic silver halide emulsion comprising photographic silver halide and a titanous diethylenetri'aminepentaacetic acid complex, silver halide developing agent, as described.

The described titanous ion complex silver halide developing agent is useful in developing an image in a silver salt diffusion transfer process. Accordingly, another embodiment of the invention is: in a photographic silver salt, diffusion transfer process comprising developing a latent image in a photographic silver salt layer, typically a photographic silver halide layer, with a titanous complex, silver halide developing agent and precipitating an image in an image receiver layer, the improvement comprising developing the latent image with a titanous diethylenetriaminepentaacteic acid complex, silver halide developing agent, as described.

One of the important properties of the developing agents employed in the practice of the invention is that the developing agents enable the described process to be carried out at a wide pH range. The activating pH can be about 1 to about 10, with good results being obtained when the pH is about neutral, i.e. about 7. This optimum pH for any particular diffusion transfer system will be influenced by the particular photographic element, the desired image, various addenda employed in the processing composition and emulsion and image receiver, processing conditions and the like. An advantage of employing a developing agent which enables use of a pH range of about 1 to about 10 is that no alkaline development activator is needed in the processing composition. However, if developing agents are employed in combination with the described titanous complex silver halide developing agent of the invention, it can be desirable in many cases to employ a development activator in the described composition to provide a pH above about 8, e.g. about 10 to about 11. It is often desirable to avoid a pH which causes decomposition of the described titanous complex, silver halide developing agent, such as a pH about 11-12. Typical development activators which can be employed with the described developing agents are alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide or lithium hydroxide, as well as organic development activators, such as amines, e.g., 2-amino-ethanol, Z-methylaminoethanol, Z-dimethylaminoethanol, 2-ethylaminoethanol, 2- diethylaminoethanol, 2,2 diiminodiethanol, 5 diethylamino-2-pentanol and the like.

A photographic silver salt diffusion transfer process according to the invention can comprise the steps of exposing a photographic element comprising a photographic silver salt, typically photographic silver halide, toform a latent image in the photographic element; developing the latent image with a processing composition at a pH of about 2 to about 10, typically a pH of about 7, comprising a titanous diethylenetriaminepentaacetic acid complex, silver halide developing agent; contacting undeveloped silver salts in the photographic element with a silver halide solvent to form an imagewise distribution of a silver complex in the unexposed areas of the photographic silver salt layer; transferring at least part of the silver complex 10 to an image receiver layer contiguous to the photographic silver salt; and reducing the silver complex in the presence of development nuclei to form a visible image on the receiver layer.

Processing conditions, time of development and the like can vary depending upon several factors such as the desired image, the particular components of the described photographic element, particular developing agents, processing composition and image receiver. Typical processing is carried out under normal atmospheric conditions and is completed within about 60 seconds such as within about 10 seconds. Processing temperatures are typically about 20 C. to about 30 C.

The described photographic element, receiving element and/or processing composition can also contain toning agents. Typical toning agents which can be employed include, for example, polyvalent inorganic salts as described in US. Pat. 2,698,236 of Land issued Dec. 28, 1954; silica as described in US. Pat. 2,698,237 of Land issued Dec. 28, 1954; and heterocyclic mercaptans such as mercaptozoles, e.g. mercaptodiazoles, mercaptotriazoles, mercaptotetrazoles, and the corresponding selenoazoles.

The photographic elements, processing compositions and/or image receivers employed in the practice of the invention can contain antioxidants, such as aldehyde-bisulfite condensation products, e.g. sodium formaldehydebisulfite.

The concentrations of developing agents used in the practice of the invention can vary over wide ranges depending on the particular photographic element, processing composition, the desired image, processing conditions and the like. When a developing agent, as described, is employed in a processing composition the total concen tration of developing agents in the composition is typically about 0.01 percent to about 10 percent, preferably 1 percent to about 5 percent, by Weight, of the total processing composition. This usually corresponds to a molar concentration of titanous complex silver halide developing agent of about 0.05 to about 0.15.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 A solution is prepared by mixing the following, respectively:

Diethylenetriaminepentaacetic acid (also known as DTPA) grams Sodium hydroxide 1 Titanium (III) chloride (20% by weight aqueous 1 Sufiicient concentration to provide a pH of 4.

2 Sufficient concentration to provide a pH of 4.0.

The resulting composition has a pH of 4.0.

A photographic element is prepared by coating a gelatino, high speed silver bromoiodide, photographic emulsion on a paper support. The silver bromoiodide emulsion contains 6 mole percent silver iodide. The photographic element is sensitometrically exposed.

The described processing composition is then squeezed between the photographic element and an image receiver which is prepared by coating a polyethylene coated paper support with palladium development nuclei dispersed in a gelatino binder with a toning agent which is polymeric pyridinium salt, and a so-called restrainer, which is phenylmercaptotetrazole. The photographic element and image receiver are then pressed together by running them between two rollers. After 30 seconds, the photographic element and image receiver are peeled apart and the resulting image on the image receiver is observed.

1 1 The developed image on the image receiver has a warm gray tone, at maximum density of 0.62, a minimum density of 0.08, a desired photographic speed, and high contrast.

EXAMPLE 2 This is a comparative example.

The procedure set out in Example 1 is repeated with the exception that a processing solution containing the following components is employed in place of the processing composition of Example 1:

Titanium trichloride (20% by weight aqueous solution) cc 150 Ethylenediaminetetraacetic acid tetrasodium salt Sodium thiosulfate pentahydrate g 20 Water to 1 liter. pH adjusted to 4.0.

The resulting developed image on the image receiver has a warm brown tone, lower contrast and lower speed than the image provided in Example 1, a maximum density of 0.94 and a minimum density of 0.54.

This illustrates that the processing composition of Example 1 provides surprisingly improved image tone, higher contrast, higher photographic speed, with surprisingly improved minimum density.

EXAMPLE 3 The procedure set out in Example 1 is repeated with the exception that the processing composition containing the following components is employed in place of the processing composition described in Example 1:

Diethylenetriaminepentaacetic acid (DTPA) g 5.389 Allylamine mls.. 2.5 Titanium (III) chloride (20% by weight aqueous solution) ml 6.5 Ethanolamine ml 2.5 Potassium iodide g 0.5 Sodium thiosulfate pentahydrate g 2.8 Water to make 100 ml. Thickener (Natrasol 250 H) g 2.2

This processing composition has a pH of 7.7.

The resulting developed image on the image receiver is gray in tone, has contrast and speed similar to those of Example 1, has a maximum density of 0.91 and a minimum density of 0.08.

EXAMPLE 4 Similar results to Example 3 are achieved when the procedure is repeated with the exception that benzylamme is employed in place of allylamine.

EXAMPLE 5 Similar results to Example 3 are achieved when the procedure is repeated with the exception that triethanolamine is employed in place of allylamine.

EXAMPLE 6 Similar results to Example 3 are achieved when the procedure of Example 3 is repeated with the exception that trimethylamine is employed in place of allylamine.

Similar results are also achieved employing the procedure of Example 3 with the exception that other amines as set out in U.S. Pat. 3,179,514 of Kirby issued Dec. 4, 1962, are employed in place of allylamine.

EXAMPLE 7 The procedure set out in Example 1 is repeated with the exception that the following processing composition is employed in place of the processing composition described in Example 1:

Diethylenetriaminepentaacetic acid (DTPA) g 5.477 Allylamine ml 2.5

Employing this procedure a developed image is provided on the image receiver which has a blue-black image tone, high contrast, photographic speed similar to the image provided in Example 1, a maximum density of 1.19 and a minimum density of 0.08.

EXAMPLE 8 Similar results are obtained employing the procedure of Example 7 with the exception that an image receiver is employed containing a combination of nickelsulfide development nuclei with silver iodide development nuclei in the image receiver in place of palladium development nuclei.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

What is claimed is:

1. In a monobath comprising a silver halide solvent and a silver halide developing agent, the improvement wherein said silver halide developing agent is a titanous diethylenetriaminepentaacetic acid complex.

2. The monobath of claim 1 which is a viscous liquid.

3. The monobath of claim 1 which has a pH of about 1 to about 10.

4. A photographic processing composition comprising a titanous diethylenetriaminepentaacetic acid complex silver halide developing agent and a silver halide solvent.

5. A photographic processing composition as in claim 4 also comprising cysteine.

6. A photographic processing composition comprising a titanous diethylenetriaminepentaacetic acid complex silver halide developing agent, an amine and a silver halide solvent.

7. A viscous, photographic processing composition comprising titanous diethylenetriaminepentaacetic acid complex,

ethanolamine,

potassium iodide,

sodium thiosulfate pentahydrate,

cysteine hydrochloride,

a thickener, and

water.

8. The method of preparing a photographic processing composition comprising the steps of (a) mixing an aqueous solution of diethylenetriaminepentaacetic acid with an alkyl amine to provide an aqueous solution, (b) mixing up to an equimolar proportion of titanium trichloride relative to the diethylenetriaminepentaacetic acid with the resulting solution, (c) adjusting the pH of the solution to about 7, (d) and then mixing a silver halide solvent with the resulting solution.

References Cited UNITED STATES PATENTS 3,595,662. 7/197 1 Willems 96-109 3,462,269 8/1969 Tassone 96-66.4

J. TRAVIS BROWN, Primary Examiner I. L. GOODROW, Assistant Examiner U.S. Cl. X.R. 96-48 

